This invention relates to an assembly fixture for the separable connection of a first component with a second component. More particularly, this invention relates to an assembly fixture for the coupling and connection of shafts or similar parts in gas turbines and in the gas turbine industry.
Assembly fixtures of the type described are known in a great variety of designs. A first method of joining shafts or similar parts to form one piece is by welding or riveting, for example.
In the case of separable assembly fixtures, as the one described herein, the use of threaded connections is known in which bolts are passed through annular flanges, for example. In addition, the mating faces of the flanges can be provided with a structure, thus creating a positive connection between the mating components and relieving the bolts of shear load during the transmission of torques.
These designs incur high effort and costs in terms of both manufacture and assembly. Furthermore, impediments exist as to the simple and accurate centering and location of the components.
A further disadvantage of the known designs lies in the fact that slip and play can occur when torsion and bending moments are transmitted.
Still another disadvantage with these designs is that ease and repeatability of component assembly with constant results cannot safely be guaranteed. Therefore, the use of curvic couplings or, alternatively, smooth interference-fit flanges known as spigots was proposed. Also, shaft connections of the conical type have been described.
While curvic couplings essentially satisfy the requirements, they are very complicated and costly to manufacture. Due to limited friction, smooth interference-fit flanges (spigots) only lend themselves for the transmission of low torques. In addition, spigots involve a relatively high assembly effort to ensure the correct location of the required interference fit, in particular due to the need for special tooling, such as presses and ovens.
The known conical designs, while being self-centering, involve additional positional tolerances both axially and linearly and do not provide for reproducible assembly results. In addition, the self-locking effect of the friction cone can impede disassembly.
In the case of cone-type connections, systems are known in which, for example, a smooth, cylindrical shaft is used, onto which the component to be attached is installed. This component is provided with a cone on the recess or hole which faces the shaft. For attachment, a ring cone is clamped between the component and the shaft. A weight and space-saving connection of shafts, in particular hollow shafts, is virtually impossible with this system.
In another design, it was proposed to provide one of the two components with a conical recess into which the cone of the other part is forced. However, this design may entail problems in terms of centering and axial alignment. Furthermore, manufacturing inaccuracies can create problems in terms of accuracy and reproducibility of the assembly.